2. This is a joint filing by Austin W. Marxe (Marxe) and David M. Greenhouse (Greenhouse). They share voting and investment control over all securities owned by Special Situations Fund III QP, L.P. (QP), Special Situations Cayman Fund, L.P. (Cayman) and Special Situations Private Equity Fund, LP (PE), respectively. 974,026 shares of Common Stock are held by QP, 1,839,385 shares of Common Stock are held by Cayman and 1,369,424 shares of Common Stock are held by PE. The interest of Marxe and Greenhouse in the shares of Common Stock owned by QP, Cayman and PE is limited to the extent of his pecuniary interest.

Austin W. Marxe

03/11/2010

David M. Greenhouse

03/11/2010

** Signature of Reporting Person

Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person,
see
Instruction
4
(b)(v).